Olivia Munn "unintentionally" lost 12 pounds on the set of 'X-Men: Apocalypse'.

Olivia Munn

Olivia Munn

The 35-year-old actress - who stars as Psylocke in the Marvel movie alongside the likes of Jennifer Lawrence and Michael Fassbender - dropped the impressive amount whilst working out for her role as the superheroine.

She said: "It was not intentional. I was trying to learn how to do all of the stunts. My character's the last to be brought into the story. They weren't expecting Psylocke to do a lot of fighting in the movie, but when I had signed on, I said that's something that I really wanted."

The 'Ride Along 2' star feared that if she didn't do the fight scene herself than it would be cut from the film's final edit.

She added to E! News: "So when they brought in my stunt person ... she was very capable and very athletic, but she had never done any stunts before, and I had grown up doing Taekwondo. I'm like, this is Psylocke's entry into this world, I'm not Jennifer Lawrence, if they don't have it, they're not gonna make sure to get it in there somehow. If there's not a fight scene being shot, if they don't have it, they're not gonna use it.

"If I wanted the fans to see Psylocke and get a good fight scene for her and the fans, I knew I had to go do it myself. So I started training every day with Taekwondo and sword and the stunt and wire work, and I just ended up losing 12 pounds from working out every day."

Meanwhile, Olivia recently revealed she would only accept her role in 'X-Men: Apocalypse' if she wasn't there to just be "eye candy".

Recalling her early meetings with the 'X-Men' producers, she shared: "I said, 'Is there a fight scene?' ... The fight scene could be her monologue.

"I thought Psylocke was always one of the most lethal characters, and I said, 'Yes, as long as you're not using her to be the eye candy. She has really powerful abilities.' And they said, 'Yes, that's an important part.'"